Morton Hears a Moo is an episode in Specy Spooktacular V.
A tired Pranky approaches a chair to rest on, but quickly sees a whoopee cushion laid on the seat. So instead he sits on a nearby stump. However, his pants get stuck to it and he wounds up taking them off in front of Morton and Mix, who have covered the stump with glue as another elaborate prank. Pranky vows to get them back.
That evening, Morton and Mix head home, when the former is distracted by the sound of a moo. The sound leads him to a dandelion, which upon close observation, appears to have a tiny cow living on it. Astonished, Morton tries to show Mix his discovery. Mix takes a close look at the dandelion but finds nothing peculiar.
Morton, carrying the dandelion in his hand, looks around for something to verify his evidence. He finds Celeste with her telescope and brings Mix to the scene. Morton holds the dandelion in front of the telescope lens in order to show them the tiny cow. Neither Mix or Celeste are convinced. Morton hears the tiny mooing sounds but fails to get his friends to hear it.
Just then, the wind blows off the dandelion's seeds, worrying Morton. A concerned Mix assumes he is losing his mind. Morton hears another moo and spots a tiny cow crossing the sidewalk. However, Ellie is rollerblading right towards it. Morton leaps in the way, bumping Ellie off the ground and sending her right into Celeste's telescope. When Mix comes over, Morton tries to explain about the tiny cow he saved, but the animal has vanished.
Tired of his friend's odd behaviour, Mix goes home. No sooner does Morton start seeing even more tiny cows in his path. Worse yet, nobody else is able to see them; even Daydream thinks he's crazy. Morton's sanity does gradually slip as the sightings continue. An attempt to capture a tiny cow on video has left him only with grainy footage and more non-believers.
One day, Morton sees Aurora at his doorstep, along with Mix, who hangs his head in shame. Aurora has the bull strapped in a straitjacket and taken on a ride to a mental hospital. Mix waves goodbyes as the ambulance disappears in the horizon. Just then, Mix hears a moo and turns to find a tiny cow beside him. Utterly shocked, he runs after the ambulance to get Morton back.
As Aurora watches the road, she too witnesses a tiny cow walking across. Swerving to avoid it, her vehicle smashes into Mix. The tiny cows are then revealed to be holograms set up by Pranky to get back at Morton and Mix. Just as he enjoys his victory, the ambulance crashes into him. Morton tumbles out of the back door with severe head trauma, going completely insane as the last things he sees are visions of tiny cows circling his head.
Celeste goes stargazing that night and spots a cow jumping over the moon through her telescope. She becomes dumbfounded at what she just saw.
"Don't have a cow."
- Ellie is impaled on Celeste's telescope.
- Mix and Pranky are hit by Aurora's ambulance.
- Aurora and Morton die in the crash, the latter more gradually.
- The title and some parts of the plot are a reference to the Dr. Seuss story Horton Hears a Who.